DNS/Message_Sizeについて、ここに記述してください。
1. flag day 2020
Note that this recomendation is for a default value, to be used when better information is not available. Operators may still configure larger values if their networks support larger data frames and they are certain there is no risk of IP fragmentation. DNS server vendors may use higher (or lower) packet sizes if better information about the MTU is available from the kernel.